Learning & memory Flashcards
key features of life-long learning
- transfer & adaptation
- overcoming catastrophic forgetting (not forgetting previous training when learning new tasks)
- flexibility (exploiting task similarity & task-agnostic learning)
- Noise tolerance
- Resource efficiency & sustainability
HM
lost part of the medial temporal lob incl. hippocampus. HM had anterograde amnesia which provided the first evidence for localisation of memory (medial temporal lobe being responsible for transition from STM to LTM as HM had LTM and working memory but couldnt form new explicit LTM)
classification of long term memory
Explicit (declarative) -> semantic (facts) & episodic (events)
Implicit (non-declarative) -> unconscious and measured by actions (four types)
Types of implicit memory & their locations
Priming (neocortex)
Procedural (striatum of basal ganglia)
Associative (classical conditioning) -> emotional responses (amygdala), skeletal musculature (cerebellum)
Nonassociative: habituation & sensitisation (reflex pathways)
Monkey experiment on working memory
Using treat found under certain object -> examine working memory of which object hides reward after a variable delay.
Lesions of the medial temporal lobe showed more removed correlated to lower memory score.
With the lesions, percentage correct was same as normal with a minimal delay (8-10 secs) however rapidly dropped off from 15-30seconds therefore: medial temporal lobe is involved in the transition from short term to long term memory
types of working memory
Two subsystems:
Verbal information
Visuospatial information
Functioning of these subsystems is coordinated by the executive control processes
Areas involved in verbal working memory
Phonological storage depends on posterior parietal corticies
Rehearsal partially depends on Brocas area
Areas involved in visuospatial working memory
representation in the parietal, inferior temporal and extrastriate occipital cortices
These representations are modulated by the frontal and premotor cortices
Processing episodic memory
Encoding, storage, consolidation, retrieval
Retrieved memories become active again which means old memories can be encoded again
Experiment on retrieval
Partially vs fully cut corpus callosum for top down retrieval (stimulus shown on different sides) shows that the prefrontal cortex contributes to recall of associated knowledge
Experiment on consolidation
Shows that during sleep or after active behaviour there will be replay of sequences that occurred during the active behaviour.
Studied using place cells in the hippocampus of rats
Experiment on habituation
Performed on aplysia studying gill withdrawal reflex
Habituation occurred by depression of synaptic potentials between sensory & motor neurons (sensory still reacts but motor doesnt)
Reflex came back after a while (not forgotten just repressed)
Neural pathway of learned fear
Can go direct from thalamus or indirect via cortex (eg auditory). Goes to lateral nucleus of amygdala, then central nucleus
Wernickes aphasia
Sensory or receptive aphasia
Fluent speech, little repetition
Adequate syntax and grammar
Contrived/inappropriate works
No comprehension
Therefore: wernickes = comprehension of language (perceive and analyse language)
Brocas aphasia
Motor/expressive/production aphasia
Halting speech
Tendency for repetition
Disordered syntax & grammar
Comprehension intact
Therefore: brocas area = how to produce words
Right vs left hemisphere functions for language
Left (slightly thicker temporal lobe):
Lexical and syntactic language
Writing & speech
->this is where brocas and wernickes areas are
Right:
Emotional colouring of language (inflection and emphasis)
Rudimentary speech
-> right does spatial tasks
What is alexia & lesion that causes it
word blindness: ability to write but not read it back
Can recognise individual letters but not associate them as sounds
Lesion causing it destroys left visual cortex and interrupts fibers from right visual cortex to on their way to left hemisphere language centers
gene thought to be involved in language
FOXP2
Schaffer collateral synapses
Use NMDA receptors for LTP of synapse
where & what are place cells
in the hippocampus, activity correlates with specific places in the environment
Are active when youre in a certain place AND if something happens in that place (association)
NOT topographically mapped (place identities are incredibly labile - adjust to every different environment we can be in)
where & what are grid cells
in the medial entorhinal cortex, fire at discrete intervals (mapping different points in our environment)
